“Om namo dev devay” is not a standard Jain mantra found in canonical Jain scriptures. In Jain practice, the most widely recited mantras are the Navkar Mantra and other stotrams dedicated to the Arihants, Siddhas, and Tirthankaras. If your aim is to chant prayers in the Jain tradition, you may consider these well-known formulations:

• Navkar Mantra (the most foundational Jain prayer)

Original (short form): Namo Arihantanam, Namo Siddhanam, Namo Ayariyanam, Namo Uvariyananam, Namo Loe Savva-sahunam. Meaning (simple): I bow to the Arihants (enlightened beings), to the Siddhas (liberated souls), to the Ayagiris/Tirthankaras who show the path, to the teachers who guide the seekers, and to all living beings who are worthy of reverence.

• Additional common line (often said after Navkar in many contexts):

“Namo Varshavanam” and related salutations to the entire chain of spiritual beings.

Notes:

• The word “Om” is a universal auspicious sound, but in Jain practice the focus is typically on sutras and mantras that explicitly praise the path to liberation and the Tirthankaras, rather than generic deva worship found in some other traditions.
• If you were aiming for a specific Jain stotra or a line from a particular sect (Digambar or Shwetambar) and you have a precise spelling or context, share it and I can give a precise explanation and, if needed, the exact original text and its meaning according to that tradition.

If you want, I can provide the exact Sanskrit verses of the Navkar Mantra with transliteration and a short, traditional arth (meaning) for each line, along with notes on any Digambar vs. Shwetambar variations.